This invention relates to escape ladders, and more particularly to a safety ladder which is compact for storage, readily deployable, and safe when deployed.
A successful safety ladder for the home should be able to meet a number of often-conflicting requirements. Typically the ladders are used for emergency egress from a second story of a home. A typical window represents the exit point, and the safety ladder must be capable of reliably attaching to a rigid structure near the window, and deploying a suspended length of treads through the window to the ground. Among the desirable characteristics are (a) a secure attachment to the building so that it will support the weight of an adult, (b) ready and user-friendly deployment, such that it will be reliably deployed in a high stress situation, (c) a nested and un-deployed condition which is both small for ready storage and assembled to avoid tangles and the like during deployment, and (d) an appearance and mode of deployment which will sufficiently inspire the confidence of a person about to use it.
Various forms of ladders have been devised which are capable of meeting some of these requirements in varying degrees. For example, a number of designs have been provided which utilize metal rungs which have standoffs to space the rung a short distance from a wall, and which have a cross-sectional shape adapted to allow the rungs to be nested. Wires or ropes or woven webbing material have been used to connect such rungs, which ultimately can provide a relatively small rung package. Readily releasably overwrap can be used to hold the rungs in the nested configuration. However, with the miniaturization of the rungs, the tendency is to also miniaturize the hooks which attach the ladder to the wall. Typically, the hooks will simply be placed over the wall at a window opening so that they span from a position just inside the window, over the wall, to a position outside the window. The ladder is suspended from the hooks. It is preferable to avoid the need for special purpose attachments on the wall, because users will attempt to resist those. However, the use of relatively small hooks, while aiding in reducing the size of the un-deployed package, potentially creates the problem of poor retention of the ladder to the structure wall.
Relatively larger hooks have been used with success. For example, the assignee of the present invention has used hooks exemplified in their commercial catalog, published September 1998, page B-10, models KEL-15, KEL-15 PLUS, and KEL-25, which are sufficiently large to reliably engage the wall for support on both the inner and outer faces thereof, and to suspend the ladder from the properly engaged hooks. Hooks of this sort have been used with chain type escape ladders where the rungs are carried on a length of chain, and in the un-deployed condition, the rung/chain package is similar in size to the overall hooks. It would be possible to utilize nested metal rungs with such hooks to provide a safe and secure assembly, but the nested configuration of the package would not attract those consumers who have an interest in minimizing the storage space required for the escape ladder.
In view of the foregoing, it is a general aim of the present invention to provide a new emergency escape ladder utilizing nested metal rungs and providing the wall-attachment reliability of a large hook design yet reducing the overall size of the nested package.
In that regard, it is an object to provide a hook configuration for such a ladder which in the un-deployed condition is of a size compatible with the nested rungs yet in the deployed condition provides safe and secure attachments to the structure.
It is a feature of the present invention to provide an escape ladder having a hook assembly comprising two laterally spaced clamps that fold into an un-deployed condition that is small as well as being compatible in size with the nested rungs to form an un-deployed package that minimizes the storage space needed for the escape ladder.
It is a further feature to form the clamps of an upper hook and a lower hook which are hinged such that the free ends of the upper and lower hooks can overlap when the hook assembly is in the un-deployed condition to form a small package for storage.
Other objects and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.